1. Field of the Invention
The present invention relates to brominated polyphenylene oxide which may be added to resin to give resin moldings being excellent in flame retardancy, electric properties, physical properties, thermal stability and appearance and which does not cause mold corrosion during molding, and to a flame retardant which employs the brominated polyphenylene oxide.
2. Description of the Related Art
For making resin such as glass fibers-reinforced polyamide resin resistant to flames, used are various condensed bromine compounds that bleed little. For example, JP-A-51-47044 discloses addition of a polystyrene bromide compound; JP-B-60-54347 discloses addition of a tetrabromobisphenol A-polycarbonate compound; JP-A-64-11158 discloses addition of a halogenoepoxy oligomer. On the other hand, JP-B-56-2100 discloses a brominated polyphenylene oxide compound. When compared with other types of bromine-based flame retardants, the compound is good in its thermal stability, heat resistance and mechanical properties, and therefore, it is specifically noticed as a flame retardant that has the ability to sustain the physical properties of even thin-walled resin products that are suitable to recent small-sized parts and members. However, the brominated polyphenylene oxide-based flame retardant that has heretofore been provided in the art often corrodes molds when the process temperature is high, and it may have some negative influence on the color tone and the thermal stability of the moldings containing it, and these problems with it began to surface.
To solve the problems, JP-A-61-118457 proposes combination with hydtotalcites; JP-A-63-150349 proposes combination with hydroxides of alkali metals of Group I of the Periodic Table or alkaline earth metals of Group II thereof; JP-B-3-153747 proposes combination with hydrotalcite, zeolite and a boron compound; and JP-A-7-252407 proposes combination with lactoaluminosilicates. However, their effects are all still unsatisfactory, and the problem of mold corrosion could not be basically solved as yet.
The invention has been made in consideration of the above, and its one object is to provide a brominated polyphenylene oxide which may be added to, for example, polyester resin or polyamide resin to give resin moldings being excellent in flame retardancy, electric properties, physical properties, thermal stability and appearance and which does not corrode molds during molding, and to provide a flame retardant that comprises it.